Device for the manual metering of a medical fluid, particularly bone cement

ABSTRACT

A device for the manual metering of a medical fluid, such as a hardening resin of the bone cement type, comprises a chamber for the fluid to be metered ( 2, 102 ) with an end opening ( 6 ), a gripping handle ( 7, 107 ), a piston ( 10, 110 ) which is housed in the chamber ( 2, 102 ) and provided with an operating member ( 12 ) for a user, and screw-type actuating means ( 13 ) arranged in between the operating member ( 12 ) and the piston ( 10 ) so as to perform the longitudinal movement thereof and pressurise the fluid to be metered. The screw means ( 13 ) may be modified so as to change from an operative configuration, where the piston is fed micrometrically, to an inoperative configuration, where the piston may move freely. The screw means ( 13 ) comprise an outer thread ( 14, 114 ) associated with the piston ( 10 ) and a female-thread element ( 15, 115 ) formed integrally on the handle ( 7, 107 ); the handle may be deformed elastically by means of transverse compression so as to change the screw means ( 13 ) from their operative configuration to their inoperative configuration.

TECHNICAL FIELD

[0001] The present invention relates to a device for the manual meteringof a fluid for medical applications, such as a medical product in aliquid or paste state, a bone cement, a gypsum or a similar material.

[0002] The device according to the invention preferably has a practicalapplication in vertebral plastic surgery and in other medical treatmentsand in general in all sectors of medicine in which it is necessary todeliver and meter in a controlled manner a product which is in a plasticor viscous state and is prepared, as required, for medications,operations or surgery.

BACKGROUND ART

[0003] Metering devices of the type indicated above are known andgenerally comprise a substantially cylindrical metering chamber with anoutlet opening for the fluid or resin to be metered, a gripping handlewhich can be fixed to the metering chamber, and a rod with a pistonhoused in the metering chamber in order to expel the fluid through theoutlet opening. The piston is located at a longitudinal end of a rodwhich has at its opposite end an operating member which may be actuatedmanually by a user.

[0004] In order to allow accurate metering under pressure, especiallywhere the fluid is in paste form or has a high viscosity, screw-typeactuating means are envisaged and essentially consist of a thread whichis formed on the outer surface of the rod with the piston and isintended to co-operate a female thread associated with the meteringchamber. By imparting a rotation to the threaded rod by means of theoperating member, the piston is made to move along the metering chambercausing the resin to be expelled in a controlled manner.

[0005] An example of a metering device of the type mentioned above isillustrated in German application DE-A-3,443,167. A drawback of saidknown device consists in the fact that, in order to fill the meteringchamber in situ with the resin or bone cement to be metered, it isnecessary to rotate the threaded rod in the opposite direction to thatof delivery, which requires a certain time during which the resin mayharden at least partially, reducing its fluidity and plasticity.

[0006] In order to prevent this problem, a number of manual meteringdevices of the type illustrated in European patent applicationEP-A-1,054,231 and French application FR-A-2,690,332 have been proposed,in which the metering chamber is provided with a lateral opening—whichis different from the outlet opening—for the introduction of the fluidto be metered into the chamber.

[0007] The opening for introducing the resin is connected by means of aconnecting line to a storage tank or an auxiliary syringe forintroducing the fluid, which must necessarily be loaded beforehand inone of said auxiliary containers.

[0008] A drawback of said known former solution consists in its relativecomplexity and dimensions. Moreover, the procedure of transferring thefluid into the chamber is fairly long and elaborate and may lead to thepartial hardening of said resin.

[0009] Dispensers of plastic fluids, such as gypsum or mastics, areknown from U.S. Pat. No. 4,485,944 and U.S. Pat. No. 5,253,589, in whichit is possible to change over from actuation of the piston with screwmeans to direct longitudinal actuation without screw means.

[0010] Another device of this type, which has the specific function ofperforming vertebral plastic surgery operations, is described inEuropean patent application EP-A-1,157,677 and comprises a piston whichmay be actuated either with a screw mechanism or by means of a simplelongitudinal movement without a screw mechanism. In particular, thefemale thread is formed by teeth which engage with the threaded rod insuch a way as to transform the rotary movement of the threaded rod intothe translatory movement of the piston. However, by moving the teethaway from the threaded rod, this rod may be freely moved axially so asto exert direct pressure on the bone cement. For this purpose, the teethmay slide inside the gripping handle against the opposing action of aspring and may be moved away from and towards the threaded rod byoperating a lateral slider which protrudes from the handle.

[0011] Owing to this configuration, after operating the slider in orderto move the teeth away from the threaded rod, the bone cement may bepressurised inside the metering chamber, both during intake and duringdelivery, as occurs with a normal syringe. At this point, after bringingthe teeth towards the threaded rod by operating the slider, it ispossible to perform micrometric feeding of the piston by rotating theoperating member.

[0012] The main drawback of this known device consists in thesignificant constructional complexity of the mechanism for actuating theteeth, as well as the large number of component parts, resulting in theconsequent high cost of the device as a whole.

[0013] This significant cost makes it disadvantageous from acost-related point of view to use the device once only and thereforeresults in the need for the device to be cleaned and sterilised in anautoclave or applying other methods every time it is used, with theresultant need to use materials which are of high quality and/orresistant to heat and sterilisation procedures.

[0014] Another and perhaps greater drawback consists in the fact thatthe lateral slider must be moved with one finger of the hand while theother fingers grasp the handle and this makes the operation ofdisengaging the teeth difficult, especially where fluids and moistureare present in the operating area.

[0015] It is therefore possible that the doctor or surgeon, whose handsare normally covered in blood and other body fluids, will be unable tooperate the slider easily and will be forced to ask for help or to usethe other hand, in circumstances where it is necessary to act rapidly,also because the cement hardens in just a few minutes.

[0016] Last but not least another drawback consists in the fact thatsaid known device has a slider on just one side, in particular on theleft side, so as to allow the threaded rod to be actuated with the righthand, and therefore cannot be easily used by left-handed people.

[0017] It would be convenient to have a metering device which is morefunctional and can be handled easily compared to known metering devicesin all conditions of use and by any user.

[0018] Moreover, it would be desirable to have a metering device whichhas a greater constructional simplicity so as to reduce its productioncost considerably. In this way, after its initial use in conditions ofmaximum hygiene and safety, the metering device could be thrown away,avoiding laborious and costly cleaning and sterilisation operations.

DISCLOSURE OF THE INVENTION

[0019] A main object of the present invention is that of designing animproved metering device which allows a fluid at high pressure to bemetered micrometrically and to be used like a traditional syringe andwhich has characteristics of high effectiveness and ease of handlingwith just one hand.

[0020] A further object is that of providing a metering device having anextremely simple structure and low cost structure so that it may bethrown away after every single use.

[0021] Last but not least another object is that of providing a meteringdevice which may be made of materials which are not expensive and withcomponents which may be obtained easily on the market so as to makedisposable use thereof convenient.

[0022] These objects, as well as others which will emerge more clearlyhereinafter, are achieved by a device for the manual delivery of amedical fluid, such as a hardening resin of the bone cement type, whichcomprises, according to claim 1, a metering chamber for the fluid withan end opening, a gripping handle, a piston which is housed in saidchamber and provided with an operating member for a user, and screw-typeactuating means arranged in between said operating member and saidpiston so as to perform the longitudinal movement thereof and pressurisethe fluid to be metered, it being possible to modify said screw means soas to change from an operative configuration, where the piston is fedmicrometrically, to an inoperative configuration, where the piston maymove freely, characterized in that said screw Wyleans comprise an outerthread associated with said piston and a female-thread element formedintegrally on said handle, said handle being elastically deformable bymeans of transverse compression so as to change said screw means fromsaid operative configuration said inoperative configuration.

[0023] Owing to this configuration, the device according to theinvention will have an extremely simplified structure which allows it tobe changed from a configuration for micrometric feeding to that of asimple manual syringe, with an extremely simplified structure and anextremely low production cost so as to avoid its repeated use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further features and advantages of the invention will be moreclearly understood from the detailed description of some preferred, butnot exclusive embodiments of a device for the manual metering of afluid, illustrated by way of a non-limiting example with the aid of theaccompanying drawings in which:

[0025]FIG. 1 shows a general view of the delivery device during use in avertebral plastic surgery operation;

[0026]FIG. 2 shows a general perspective view of a first embodiment ofthe device shown in FIG. 1 in an assembled condition;

[0027]FIG. 3 shows a general perspective view of the device shown inFIG. 2 in partial cross-section and with some parts removed in order tomake its components easier to see;

[0028]FIG. 4 shows an exploded perspective view of the device shown inFIG. 2;

[0029]FIG. 5 shows a perspective view of a sub-assembly of the deviceshown in FIG. 2 without some components so as to illustrate more clearlyfunctioning of the device;

[0030]FIG. 6 shows a side view of the device shown in FIG. 2, partiallycross-sectioned along a longitudinal axial plane;

[0031]FIG. 7 shows a front view of the device shown in FIG. 2, partiallycross-sectioned along a plane indicated by the line VI-VI shown in FIG.5;

[0032]FIG. 8 shows a general perspective view of a second embodiment ofthe device shown in FIG. 1, in an assembled condition;

[0033]FIG. 9 shows a perspective view of the device shown in FIG. 8,with some parts separated from the rest of the device.

DETAILED DESCRIPTION OF SOME PREFERRED EMBODIMENT

[0034] With reference to FIG. 1, a metering device according to theinvention is shown, said device being denoted in its entirety byreference number 1 and used to deliver a fluid, for example an acrylicresin or bone cement, manually into a location which is difficult toaccess, for example the inner cavity of a vertebra, by means of a thintube H coupled to a needle N.

[0035] The device described hereinafter is particularly suitable forperforming an orthopaedic surgery operation known as vertebral plasticsurgery, for treating or restoring the continuity of a vertebra Vaffected by injuries or disease. It is clear, however, that the devicemay be used for other treatments and surgical or medical operations,using fluids of varying density or viscosity, or in other technologicalsectors, without thereby departing from the scope of the invention.

[0036]FIGS. 2-7 show a first embodiment of the device 1 which comprisesa metering chamber 2 which has a substantially cylindrical side wall 3and is intended to receive the hardening resin or bone cement inside it.

[0037] A longitudinal end of the side wall 3 of the chamber is open andstiffened by a radial flange 4. At the other end there is a tapered orfunnel-shaped duct 5 with an opening 6 for the passage of the resin. Aneedle N may be connected to the funnel-shaped duct 5 directly or bymeans of the thin tube H so as to carry the resin to the site to betreated.

[0038] Optionally, the metering chamber 2 may be formed by the body of atraditional syringe made of plastic material, of the type which iswidely available on the market, so as to reduce the cost of the deviceas a whole.

[0039] A handle, denoted in its entirety by reference number 7, may beassociated with the chamber 2 by means of a suitable interface element8. This element may be formed by two opposite shells 8′, 8″ which arecoupled together by means of suitable connecting members 9 of theinterlocking type or using any other adhesive means.

[0040] Advantageously, the walls of the shells 8′, 8″ may be providedwith projections able to retain the handle 7 stably in the region of abayonet-type lateral expansion 7′ associated therewith as well as theradial stiffening flange 4 of the wall 3 of the metering chamber 2.

[0041] A piston 10 is housed inside the metering chamber 2, said pistonoptionally being provided with a sealing ring 10′ and located at alongitudinal end of a rod 11 having keyed onto its opposite end a knobor other operating member 12, which may be grasped by a user in order tofacilitate the expulsion of the resin located inside the chamber 2.

[0042] Conveniently, in order to actuate the rod 11 and expel the fluidor resin located inside it at high pressure and in a controlled manner,screw means are envisaged, said screw means being denoted in theirentirety by reference number 13 and comprising a helical thread 14formed on the cylindrical surface of the rod 11 and a female-threadelement 15 which is able to engage with the thread 14 but is lockedaxially and rotatably with respect to the wall 3 of the chamber 2.

[0043] In this way, in order to perform micrometric feeding of thepiston 10, with corresponding metering of the cement or fluid to bedelivered, it is sufficient to grasp the knob 12 and make it rotate in aclockwise or anti-clockwise direction, depending on the direction of thethread 14, thereby causing the rod 11 to move axially and therefore thepiston 10 to move inside the chamber 2 in the direction indicated by thearrow M.

[0044] In order to allow the piston 10 to slide freely inside thechamber 2 without using the screw means 13 and therefore speeding up theoperations of filling the chamber 2, the screw means 13 may be modifiedso as to change from an active configuration to an inactive position andvice versa. In particular, the female-thread element 15 is formed by aninternally threaded cylinder portion 15′ which may be moved from anoperative configuration—engaged with the thread 14 of the threaded rod11 in order to allow micrometric feeding of the piston 10—to aninoperative configuration out of contact with the rod 11.

[0045] In this way, in order to draw the resin into the chamber 2, it issufficient to disengage the female-thread element 15 from the thread 14and pull the threaded rod in the direction of the arrow T by operatingthe knob 12.

[0046] Moreover, in the event of excessive pressure of the resininjected into the operating site, it is possible to reduce the pressureimmediately by disengaging the female-thread element 15 from the thread14 and therefore allowing the piston 10 to move backwards in the chamber2.

[0047] According to the invention, the female-thread element 15 isformed integrally on the handle 7 in an area facing the threaded rod 11.Moreover, the handle 7 may be deformed elastically by means of simpletransverse compression in the direction of the arrow P so as to move thefemale-thread element 15 into its inoperative configuration, i.e.separated from the thread 14, in order to prevent them from beingengaged.

[0048] Preferably, the handle 7 is a substantially U-shaped unitary bodywith a first longitudinal end portion 16 which may be coupled to thechamber by means of the interface element 8 and a second longitudinalend portion 17 bearing the female-thread element 15.

[0049] Conveniently, the two longitudinal end portions 16, 17 of saidU-shaped body are substantially rigid and are joined by an elasticallydeformable transverse intermediate portion 18.

[0050] In particular, the internally threaded cylindrical cylinderportion of the female-thread element 15 may be formed on the outer sideof the longitudinal arm 17 of said substantially U-shaped body.

[0051] Even more in particular, the longitudinal arms 16, 17 are formedin such a way that the internally threaded cylindrical portion 15 isnormally in contact with the thread 14 of the rod 11 and may be movedaway from said rod by bringing the longitudinal arms 16, 17 of the knob7 closer together transversally.

[0052] Conveniently, the corners of the longitudinal arms 16, 17 and ofthe transverse arm 18 are rounded so as to allow a user to grasp thehandle and compress it easily with all the fingers of one hand, be itthe left hand or the right hand, with ease even in the presence of bodyfluids and moisture in the surrounding environment.

[0053] The longitudinal arm 16 may have a bayonet-shaped free end whichmay be retained by first half-shell formations 8′, 8″ of the interfaceelement 8.

[0054] In order to manufacture a device according to the invention, itis sufficient to make its various parts out of low-cost plasticmaterial, then assemble it and sterilise it before it is packed.

[0055] In particular, all the components of the device may be made bymeans of the injection and moulding of low-cost plastic materials,providing that they allow the same end results to be obtained.

[0056] Owing to the significant constructional simplicity and lowmanufacturing cost, it is possible to use the device once only, avoidingthe considerable costs of cleaning and sterilising the device.

[0057] It can be observed that the particular form and structure of thehandle 7 allows the device to be gripped easily and stably and operatedin a simple manner by any user, without any risk of malfunctions orslipping, even in the critical conditions that arise during a surgicaloperation.

[0058] Moreover, whenever it is necessary to reduce the feeding pressureof the resin delivered by the device, in the event of excessive pressurein the medullar cavity of the vertebra or the bone to be treated, it issufficient to grip the handle 7 more tightly with all the fingers of thehand so as to disengage the female-thread element from the threaded rod11 immediately, allowing the cement to flow back towards the meteringchamber 2.

[0059] In the second embodiment shown in FIGS. 8, 9, denoted in itsentirety by reference number 101, the same components that are alsopresent in the first embodiment are identified by the same referencenumbers increased by 100.

[0060] This second embodiment differs from the preceding embodiment onlyin respect of the interface element 108, which has the function ofconnecting the handle 107 to the metering chamber 102 formed by the body103 of a traditional syringe with a stiffening flange 104.

[0061] The interface element 108 is essentially formed by a unitaryblock in the form of a U-piece with a pair of vertical arms 108′, 108″which are provided internally with respective lateral slits 109′, 109″able to receive and retain stably the lateral edges of the flange 104 ofthe body 103.

[0062] Therefore, in order to associate the metering chamber 102 withthe handle 107, it is sufficient to couple the handle 107 to theinterface element, insert the rod 111 inside the wall 103 of themetering chamber 102 and couple this chamber to the interface element108 by inserting the flange 104 into the slits 109′, 109″ of the block108.

[0063] In this way, it is even quicker and easier to prepare the device,and, if necessary, syringes 103′ already filled with fluids to bemetered and protected in sterile packaging may be used.

[0064] Operation of the handle for engaging and disengaging the partialfemale-thread 115 with/from the thread 114 is otherwise identical tothat described for the device 1.

[0065] From the above, it is clear that the metering device achieves allthe predefined objects and particular attention is drawn to the ease ofhandling in all operating is conditions, even the most difficultconditions, such as those which occur in moisture-affected environments,by all users, irrespective of which hand they normally use.

[0066] The metering device according to the invention may be subject tonumerous modifications and variations, all of which fall within theinventive idea expressed in the claims. All the details may be replacedby other technically equivalent elements and different materials may beused according to the requirements, without departing from the scope ofthe invention.

[0067] Although the subject of the invention has been described withparticular reference to the accompanying drawings, the reference numbersused in the description and in the claims are used to facilitateunderstanding of the invention and do not constitute any limitation onthe protective scope claimed.

[0068] The instant application is based upon and claims priority ofpatent application no. VI2002A000140, filed on Jun. 26, 2002 in Italy,the disclosure of which is hereby expressly incorporated here inreference thereto.

1. Device for the manual metering of a medical fluid, such as ahardening resin of the bone cement type, comprising a chamber for thefluid to be metered with an end opening, a gripping handle, a pistonwhich is housed in said chamber and provided with an operating memberfor a user, and screw-type actuating means arranged in between saidoperating member and said piston so as to perform the longitudinalmovement thereof and pressurize the fluid to be metered, said screenmeans being able to be modified so as to change from an operativeconfiguration, where the piston is fed micrometrically, to aninoperative configuration, where the piston may move freely,characterized in that said screw means comprise an outer threadassociated with said piston and a female-thread element formedintegrally on said handle, said handle being elastically deformable bymeans of transverse compression so as to change said screw means fromsaid operative configuration to said inoperative configuration. 2.Device according to claim 1, in which said female-thread element is ahollow cylindrical portion with an internal thread having a pitchcorresponding to that of said outer thread associated with said piston.3. Device according to claim 1, in which said handle is a substantiallyU-shaped unitary body with a first longitudinal end portion which may becoupled to said chamber ( and a second longitudinal end portion providedwith said female-thread elements.
 4. Device according to claim 3, inwhich said longitudinal end portions (16, 17) are substantially rigidand are joined by an elastically deformable intermediate connectingportion (18).
 5. Device according to claim 2, in which said internallythreaded cylindrical portion is formed on the outer side of a free endof said second longitudinal end portion of said handle.
 6. Deviceaccording to claim 4, in which the internal thread of said female-threadelement is normally engaged with said outer thread associated with saidpiston and may be moved away from this thread by means of the transversecompression of said longitudinal end portions. associated with saidpiston and may be moved away from this thread by means of the transversecompression of said longitudinal end portions.
 7. Device according toclaim 1, in which said chamber is formed inside a substantiallycylindrical wall, said end opening being formed in a tapered portionintended to be coupled to fluid transfer means, such as tubes orneedles, and a radial stiffening flange being formed at its open end. 8.Device according to claim 7, in which said cylindrical wall is the bodyof a traditional syringe.
 9. Device according to claim 1, in which saidhandle may be coupled to said metering chamber by means of an interfaceelement.
 10. Device according to claim 9, in which said interfaceelement has a substantially box-shaped form formed by a pair of oppositehalf-shells with mutual coupling means, as well as first projectionsable to retain an end of said first bayonet-shaped longitudinal endportion and second projections able to retain axially said radial flangeof said cylindrical wall of the metering chamber.
 11. Device accordingto claim 7, in which said interface element has a substantially U-shapedform with substantially vertical arms having lateral slits for housingand fixing the lateral edges of the stiffening flange of said syringebody.
 12. Device according to claim 1, characterized in that it is madeof low-cost plastic materials and is placed inside sterile packaging soas to be used once only.